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Fri, 16 Jan 2026 06:24:19 +0000 (UTC) X-Farcaster-Flow-ID: 6875cfc2-26af-4f0a-b7d8-12d6d4c1f805 Received: from EX19D001UWA001.ant.amazon.com (10.13.138.214) by EX19MTAUWB001.ant.amazon.com (10.250.64.248) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.35; Fri, 16 Jan 2026 06:24:19 +0000 Received: from 603e5f7bc1fe.amazon.com (10.37.245.10) by EX19D001UWA001.ant.amazon.com (10.13.138.214) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.35; Fri, 16 Jan 2026 06:24:17 +0000 From: Takashi Kozu To: CC: , , , , , , , , , , Subject: Re: [Intel-wired-lan] [PATCH iwl-next v2 3/3] igb: allow configuring RSS key via ethtool set_rxfh Date: Fri, 16 Jan 2026 15:24:11 +0900 Message-ID: <20260116062410.80174-2-takkozu@amazon.com> X-Mailer: git-send-email 2.47.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: EX19D042UWA003.ant.amazon.com (10.13.139.44) To EX19D001UWA001.ant.amazon.com (10.13.138.214) > -----Original Message----- > From: "Loktionov, Aleksandr" > To: "Loktionov, Aleksandr" , > Kohei Enju > Cc: "andrew+netdev@lunn.ch" , > "Nguyen, Anthony L" , > "davem@davemloft.net" , > "edumazet@google.com" , > "intel-wired-lan@lists.osuosl.org" > , > "kuba@kernel.org" , > "netdev@vger.kernel.org" , > "pabeni@redhat.com" , > "Kitszel, Przemyslaw" , > "takkozu@amazon.com" > Subject: Re: [Intel-wired-lan] [PATCH iwl-next v2 3/3] igb: allow configuring RSS key via ethtool set_rxfh > Date: Thu, 8 Jan 2026 13:03:12 +0000 [thread overview] > Message-ID: (raw) > In-Reply-To: > > > > > -----Original Message----- > > From: Intel-wired-lan On Behalf > > Of Loktionov, Aleksandr > > Sent: Thursday, January 8, 2026 1:28 PM > > To: Kohei Enju > > Cc: andrew+netdev@lunn.ch; Nguyen, Anthony L > > ; davem@davemloft.net; > > edumazet@google.com; intel-wired-lan@lists.osuosl.org; > > kuba@kernel.org; netdev@vger.kernel.org; pabeni@redhat.com; Kitszel, > > Przemyslaw ; takkozu@amazon.com > > Subject: Re: [Intel-wired-lan] [PATCH iwl-next v2 3/3] igb: allow > > configuring RSS key via ethtool set_rxfh > > > > > > > > > -----Original Message----- > > > From: Kohei Enju > > > Sent: Thursday, January 8, 2026 1:04 PM > > > To: Loktionov, Aleksandr > > > Cc: andrew+netdev@lunn.ch; Nguyen, Anthony L > > > ; davem@davemloft.net; > > > edumazet@google.com; enjuk@amazon.com; intel-wired- > > > lan@lists.osuosl.org; kuba@kernel.org; netdev@vger.kernel.org; > > > pabeni@redhat.com; Kitszel, Przemyslaw > > ; > > > takkozu@amazon.com > > > Subject: Re: RE: [Intel-wired-lan] [PATCH iwl-next v2 3/3] igb: > > allow > > > configuring RSS key via ethtool set_rxfh > > > > > > On Thu, 8 Jan 2026 07:29:19 +0000, Loktionov, Aleksandr wrote: > > > > > > >> > > > >> - igb_write_rss_indir_tbl(adapter); > > > >> + if (rxfh->key) { > > > >> + adapter->has_user_rss_key = true; > > > >> + memcpy(adapter->rss_key, rxfh->key, sizeof(adapter- > > > >> >rss_key)); > > > >> + igb_write_rss_key(adapter); > > > >It leads to race between ethtool RSS update and concurrent resets. > > > >Because igb_setup_mrqc() (called during resets) also calls > > > igb_write_rss_key(adapter). > > > >Non-fatal but breaks RSS configuration guarantees. > > > > > > At my first glance, rtnl lock serializes those operation, so it > > > doesn't seem to be racy as long as they are under the rtnl lock. > > > > > > As far as I skimmed the codes, functions such as igb_open()/ > > > igb_up()/igb_reset_task(), which finally call igb_write_rss_key() > > are > > > serialized by rtnl lock or serializes igb_write_rss_key() call by > > > locking rtnl. > > > > > > Please let me know if I'm missing something and it's truly racy. > > I think you're right, and I've missed that missing rtnl_lock was added > > in upstream. > > > > Thank you for clarification > > Reviewed-by: Aleksandr Loktionov > > > > Afterthought, I think it could be nice to place ASSERT_RTNL() to show it explicitly. > What do you think about this idea? Sorry for the late reply. I think it's a good idea. I will add ASSERT_RTNL().